The objective of this study is to develop an optimized hearing testing and screening module, and compact portable device, that can be used to efficiently assess peripheral neural function (including retrocochlear disorders) using the medial olivocochlear reflex (MOCR). Measuring neural function via the MOCR is accomplished by recording otoacoustic emissions (OAE) under conditions that elicit the neural reflex. This reflex has been shown to be abnormal in patients with neural disorders. The focus of this project will be the development of a screening module that incorporates OAE screening and measurement of the MOCR in the same test procedure. The target population in the proposed research is infants, particularly those in environments where ABR screening is not performed routinely. Addition of the MOCR to screening where ABR is not performed will address the shortcoming of OAE screening which misses neural forms of hearing loss. While infant screening is the focus of the data that will be acquired, optimizing the ability to assess the MOCR in ipsilateral and binaural conditions, in addition to the already feasible contralateral condition, will open additional clinical applications in children and adults. This team has a record of research related to the MOCR, neural hearing loss, and integrating a MOCR paradigm into a clinical system that provides the basis for a direct to Phase II application. This Phase II proposal will address accuracy, efficiency, and automation in testing and analysis, and will build on existing OAE measurement and analysis capability in systems by Intelligent Hearing Systems. Aim 1 will focus on the implementation, optimization and noise cancellation of the MOCR acquisition system. Aim 2 will focus on the development of a compact portable wireless MOCR OAE screening device. Aim 3 will perform a comprehensive evaluation of two innovative MOCR recording methods on a large number of newborns in the nursery and during the time period of follow-up testing of infants referred based on newborn hearing screening results. These techniques will also be compared to an established forward masking MOCR recording paradigm on adults. In addition, infants, children and adults with neural disorders (e.g., auditory neuropathy) will be tested.